The major objective of the University of Rochester Center for Blood Cell Rheology is enhancement of intellectual exchange and cooperation among investigators concerned with function and survival of blood cells within the microcirculation, as these parameters relate to normal or altered cellular physical properties. To accomplish this goal the Center provides an environment of intellectual interchange by supporting scientific collaboration between investigators in the Department of Medicine and Radiation Biology and Biophysics within the School of Medicine and the Institute of Optics and Mechanical and Aerospace Engineering, in the College of Engineering and Applied Sciences, and supports the physical setting to facilitate such interactions. Specific categories of research include 1) studies of cellular deformability and capillary rheology; 2) red blood cell membrane structure-function relationships and cell metabolism; and 3) pathophysiology microvascular occlusion. Erythrocyte shape determinants are investigated by optical and electron microscopic studies and the dynamics of shape change by holography. Cellular deformability and capillary microrheology investigations involve deformation studies and erythrocyte flow techniques utilizing glass microcapillaries and capillary regions of experimental animals. Electron microscopic studies of microcirculation of bone marrow with particular focus on release phenomenon of mature and abnormal cells is complemented by studies on cellular destruction in the spleen. Characterization of interactions of specific protein and lipid structural elements and comparisons of normal membrane structure with that in pathologic states utilize standard physical biochemical methodology. Studies in hemostasis focus on dynamics of platelets in capillary occlusive phenomenon.